31. How did the Black Death affect the commutation of labor service in the long run？
(A) It became faster than before.
(B) It continued, but only for a short time.
(C) It stopped it temporarily.
(D) It increased, but at a slower rate.

27. What is the main theme of this passage？ (A) The writer wants to alleviate worries about genetic mutation. (B) The writer wants to show the invisible danger and risks of radiation at work places. (C) The writer wants to identify the genetic mutations caused by radiation. (D) The writer wants to convince people of the danger of genetic defects caused by radiation.

28. The writer of this passage would possibly not agree with which of the following？ (A) The long-term effects of additional radiation should be considered before whole populations begin space travel. (B) Mutation rates can be tripled through low levels of radiation in each generation. (C) Prenatal and postnatal development are affected every little by the physical environment. (D) There is little danger of genetic mutation from medical treatment which has been neglected by the general public.

29. Which of the following headings best expresses the main idea of the passage？ (A) The Shortcomings of Computer Languages (B) How the Local Area Network Will Work (C) New Types of Hardware and Software (D) Coming Opportunities in the Computer Profession

30. According to the passage, one reason for trying to develop a computer language like English is that _____. (A) English is grammatically simple and easy to learn (B) English is an international language that more people use than any other language. (C) a language would be easier for home-computer users than the symbolic and technical languages now available but not friendly to the users (D) all of the computer programmers developing the computer language are English speaking people.

32. According to the passage, what was the commutation of labor service？ (A) A reduction in the amount of wages paid. (B) The movement of labor to industrial areas. (C) The loss of workers due to starvation. (D) A change in the status of the laborer.

33. What, in fact, was the real reason for the decline in living standards？ (A) A reduction in the amount of arable land. (B) A surplus of food supplies. (C) An agricultural revolution. (D) A huge increase in the size of the population.

34. According to the author, what characteristic of decline has been blamed on the Black Death？ (A) The abandoning of villages. (B) The lack of food. (C) The death of monks. (D) The loss of crops.

35. The Black Death came to Western Europe from _____. (A) England (B) the Crimea (C) Genoa (D) the Mediterranean

36. According to the passage, we become ill more easily when we _____. (A) act irrationally (B) are pushed too hard (C) are under stress for a long time (D) are unable to resist

37. The main difference between danger today and in the past seems to be that _____. (A) it is harder to deal with (B) it is easier to deal with (C) work and school are more dangerous (D) people at work and school like danger